Radio clockwork mechanism having a detector for setting the clock hands

ABSTRACT

The present invention relates to a radio clockwork mechanism which includes a movable hour hand and a mechanism for determining which hour the hour hand is currently indicating. That determining mechanism comprises hour-contact arches, a scanning mechanism, and a querying mechanism. The hour-contact arches are assigned to respective hours and are spaced apart a circular path. The scanning mechanism includes an hour-scanning device which is movable synchronously with the hour hand for sequentially scanning the hour-contact arches and giving a currently scanned hour-contact arch and an electrical potential different from all other hour-contact arches. The querying mechanism queries the hour-contact arches for determining which has the different electrical potential.

BACKGROUND

The invention relates to a radio clockwork mechanism having a detectorfor setting the clock hands.

A radio clockwork mechanism of this kind is known from EP 0 204 851-A2with a four bit wide angular encoder for an indirect quasi-continualelectromechanical detection of the hour-hand position. Four circles on aprinted circuit board, that are concentric relative to the hand-shaftaxis, are queried for this purpose by way of four bending springs, whichare insulated relative to one another, as to the radially sequentialexistence or non-existence of ohmic contacts in the angular positionjust achieved and which are binary coded via the contact pattern. Thisprocess is complicated in terms of mechanics and requires much space;moreover, due to the uncertainties with regard to the ohmic contactmaking in relation to the current contact pattern, such a query of thehand position is quite imprecise and, at any rate, very susceptible tointerferences.

This is the reason why said publication also takes into considerationthe possibility of representing the movement of the hand electronicallyby way of counting and storing with each hand rotation—beginningrespectively with an ohmic synchronization contact making—the driveimpulses for the stepping motor for the purpose of moving the hand. Butthe current counter result reflects the current angular position of thehand only then correctly if no slippage occurs between the electricaltriggering of the stepping motor and the subsequently resultingmechanical movement of the hand via the gear train, as well as it thereis no excessive looseness in the gear train from the drive motor to thehour-hand wheel.

It is therefore known from DE 35 13 961-C2 to detect the reaching ofseveral few (typically three) defined hand positions in the course of arotation of the hour-hand in succession and indirectly, in fact, via anoptronic sensing of different spoke widths in the hour wheel during therotational movement of the wheel mechanism. But this requires a complexalgorithm. Moreover, due to the fact that in order to achieve a cleardetection of the spoke widths in spite of the unavoidable gear loosenessseveral rotational steps must be implemented during which, respectivelyonce again, the existence or the end of the spoke widths that must beclearly distinguished are queried, any miniaturization of such a spokequery faces noticeable limits.

Building smaller is the solution described in DE 35 10 861-C2 for thetriggering of a synchronization signal with precise exactness whenpassing through a very defined, preset hand position and starting fromwhich, once again, the trigger impulses for the stepping motor arecounted. A light barrier is envisioned at that place and for thispurpose which detects the hour-hand position also indirectly, in fact,once again, on the hour-hand wheel behind the clock face. Said handwheel and the intermediate wheel, which is located ahead of the formerin the gear train thus rotating faster and even in the oppositedirection of rotation of the former, engage as circle aperture disks inthis light barrier, resulting in the fact that also large-surfaceaperture orifices not requiring much adjusting on the part of themanufacturer and still allowing a broad light beam to pass for thereliable response of the receiver of the light barrier, and ensure aresponse that is exact to the minute, e.g. when the hour wheel isqueried, due to the only very brief aperture overlap. However, sinceonly the reaching of a single, firmly preset hand position in the handrotation is queried and since a customarily used clock stepping motordoes not allow for a reversal of the direction of rotation, based on acoincidental starting position, comparatively quite a long time span maypass even with drive in accelerated mode, in particular at the beginningof start-up, until the constructively preset hand position (such as the12 o'clock position from a current 02:00 o'clock position) is reached inorder to swing the clock hands from this synchronized position into thedesired position of the current point in time and to continue with theregular operation of the radio clockwork with its time-keeping hand-timedisplay.

U.S. Pat. No. 4,148,181 describes a striking train control in which thefull hour is detected with a contact arm.

DE 19 05 950 A1 describes a device with clockwork for giving light andsound signals that can be programmed for noting scheduled appointments.In that case, a contact is closed by way of placing a concentricallyarranged contact arch on another potential than the others. When thehour hand with its fin conducts, during its rotation, the power from thecontact sector to the ring, this ring allows the function to be carriedout, noticeable by way of its connection to the light or the horn, andwhich function provides that the contact arches are queried insuccession in order to determine as to which one of them has the otherpotential that is then being displayed.

In the radio clockwork mechanism of specification DE 198 24 840 A1,which the invention uses as a basis, the individual hour-contact archesare connected to one another via a resistance matrix. In particular, twoadjacent contact arches are connected to each other by way of anelectrical resistor resulting in a serial connection of electricalresistors. A sliding contact that is connected to an hour wheel scansthe hour-contact arches. An evaluation device determines the electricalresistance value between a reference-contact arch and the currentlyscanned contact arch. The determined resistance represents an order ormagnitude that can be assigned to a certain angle position of the hourwheel.

Recognizing these circumstances, the object of the invention consists inproviding an analog radio clockwork mechanism of the said class with—forfast finding of the exact current hour-hand position even right afterthe start-up of operation and from a coincidental handposition—virtually continual monitoring of the actual movement of thehour-hand but with less inherent complexity in terms of apparatus andswitching than the class-defining, complete multi-bit angular encoding.

SUMMARY OF INVENTION

The present invention relates to a radio clockwork mechanism whichcomprises a movable hour hand and a mechanism for determining which hourthe hour hand is currently indicating. That determining mechanismcomprises hour-contact arches, a scanning mechanism, and a queryingmechanism. The hour-contact arches are assigned to respective hours andare spaced apart a circular path. The scanning mechanism includes anhour-scanning device which is movable synchronously with the hour handfor sequentially scanning the hour-contact arches and giving a currentlyscanned hour-contact arch and an electrical potential different from allother hour-contact arches. The querying mechanism queries thehour-contact arches for determining which has the different electricalpotential.

Correspondingly, a contact sequence is arranged principally along acircle and which is assigned to the division by hours of the minutedistribution ring on the face of the clock, meaning that with the usualtwelve-hour clock face, it is comprised of twelve contacts that arearranged in the shape of an arch adjacent to each other and at adistance from each other. Assigned to each of these hour-contact archesis on another circle, that is arranged concentrically relative to theformer circle and preferably located inside the former circle, ahalf-hour-contact arch extending, for example, over the second half hourof an hour respectively. The contact arches are scanned by the slidingcontact springs rotating synchronously with the hour hand of the clock,the hour and half-hour contact fingers. Preferably, these contactfingers are both lying on the ground potential therefore placing in theangular position, which has just been achieved, on the one of the twocircular paths an hour-contact arch and in the second half hour of thehour-contact arch the half-hour-contact arch on the ground potential. Adecoder logic continually queries which of the hour-contact arches iscurrently on the ground potential thereby detecting virtually withoutgaps the currently indicated hour.

If in this embodiment the angularly assigned half-hour-contact arch isnot yet on ground potential, the time indicator of the hand of the clockis in the first half hour of the current hour, otherwise in the secondhalf hour. This way, the current position of the hour hand is virtuallyalways clearly represented by means of an hour contact and within thecontext of the length of the arch of the hour contact by means of theassociated half-hour contact; thus the hand position on the clock facethat is divided into twelve hours is always determined with an accuracyof half an hour. Therefore, at the start-up of operation the clockworkmust only rotate until the change to the next half hour that follows insequence, thereby quickly indicating the exact current hand positionbased upon which it is possible to effect the defined swinging of thehands to the current, actual given point in time.

But the response to the half-hour change is plagued with insecurities ifonly because of the unavoidable gear looseness, and even more so whendealing with the ohmic contact making of the contact finger gliding ontoa contact arch. Therefore, for an exact determination of time by thehalf-hour, the contact query occurs only at a defined point in time; forthe half-hour division of hours this is preferably exactly at thebeginning of the first and of the thirtieth minute of each hour.Reliance is placed upon the light barrier detection device in accordancewith DE 35 10 861-C2 for this purpose. To provide for the possibility ofthe half-hour, exact-to-the-second position detection by way of thereferred to light barrier, in order to ensure the passage of the lightthe hour wheel is configured preferably with a total of 24 diametricallydistributed holes or, for reasons of mechanical stability, completelymade of an optically permeable material without holes. Moreover, inorder for the light barrier to respond precisely, exact-to-the minuteonly at the beginning of the given half hour, respectively, theintermediate wheel located in the gear train before the minute wheel,therefore rotating faster and in the opposite direction, also engages inthe aperture of the light barrier. A further engagement of a second-handwheel in the light barrier as well as of the intermediate wheel, whichis located before the former wheel in the gear train and rotates in theopposite direction of the second-hand wheel, as aperture disks makes itpossible to detect the half-hour position with a preciseness that isexact to the second.

For the special case of a clock face with a 24-hour division perhour-hand rotation, which is encountered sometimes, the describedcontact grouping of 12/24 contact arches on two radii would clearlyproduce a determination of the current hand position that is precise tothe hour and that would be detected at the time of the full hour with aprecision that is exact to the second by means of the above lightbarrier function.

The contacts for the quasi-continuous rough but frequent, in fact everyhalf-hour, detection of the hand position can be configured or mountedon the same side of a printed circuit board that is penetrated by thehour-hand shaft and lined with conductor paths; and on this surface saidprinted circuit board also carries the detection-evaluation circuit andthe radio clockwork circuit, which is in this case, in particular, anautonomous time-keeping circuit and receiver, decoder, comparer andmotor control the function of which is in part combined with aprocessor. The detection of the sequential contact arches dependent onhand position occurs in the described embodiment of an ohmic query bymeans of brush springs, most suitably in such a way that the decodingand evaluation circuit determines if in the context of the currentangular position of the hour hand one or two contacts are now placed onthe ground potential. Because this way it is not necessary to move anybrush springs, insulated relative to each other and rigidly in relationto each other, and to connect them via their own commutators to theevaluation circuit; in that case, it is sufficient to bend all of thebrush springs as contact fingers from a single disk made ofspring-elastic, electrically conducting material that is rigidly caughtby the hour-hand shaft and to continually place this contact disk onground potential by means of another finger over a contact ring. Thecontinual joint ground potential creates moreover the advantage of acontact query that is electrically quite interference-proof, because itis shielded in terms of the potential. In fact, within the radius of thecontacts, that are extending in the shape of an arch, this creates aspace that is electrically quite nicely shielded between the contactdisk that is on the ground potential and the circuit board in which ismost suitably arranged the optical receiver of an optoelectronicdetector, designed e.g. as a bifurcated light barrier, for the lightbarrier in the gear train of the hand mechanism for the periodic releaseof the contact query, whereby the work mode of said receiver enjoysexcellent protection against environmental influences.

It is additionally possible that another contact finger accesses theprinted circuit board, in fact in this instance a continuous contactring, from the central contact disk that is rotating with the hour hand,which is, in that case, the triggering of an alarm signal. This contactfinger as a whole is most suitably held electrically insulated by aspacer ring relative to the alarm contact ring. But for a certainangular position of the hand (which means a certain time on the clockface) the spacer ring has an interruption through which it is possiblefor the contact finger to drop down on the alarm signal trigger makingcontact when the hand is in a corresponding position, and without theneed of having to axially displace yet another wheel of the clockworkfor this alarm signal trigger. The spacer ring can be rotated around theaxis of the hand shaft which makes it possible to adjust the clickinterruption manually to a certain time at which the spacer ring remainsfrictively secured relative to the rotational movement, when the alarmcontact finger has lifted off once again from the alarm contact ring viaan ascending ramp at the click opening in order to continue beingrotated in a synchronous fashion with the hour hand on the spacer ringuntil the click opening is reached once again after a rotation of thehour hand.

In order to guide the contact disk with its contact fingers, which areflexibly supported against the printed circuit board (or the alarmspacer ring), without jamming during the rotational movement, it ispossible to configure the described group of contact fingers for thepurpose of the symmetric force distribution as offset several timesrelative to each other, approximately by 120° or 180°. This avoidsoverturning moments on the contact disk and, via the disk, on the hourshaft.

BRIEF DESCRIPTION OF THE DRAWINGS

Further improvements and variations as well as additionalcharacteristics and advantages of the invention are derived from thesubsequent description of an embodiment of the solution according to theinvention. The drawing is limited to the essential aspects and renders asketch in the approximately appropriate dimensions, wherein.

FIG. 1 depicts a partial axial longitudinal section, the wheels of anelectromechanical radio clockwork mechanism with analog displayfeaturing an angular position query according to the invention of thehour hand and an alarm signal switch that is additionally integrated inthe latter; and

FIG. 2 shows a functionally representative contact pattern for thehalf-hour query of the hour-hand position in accordance with FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT

The sketched electromechanical radio clockwork mechanism 11 is equippedfor the analog time display on the free front ends of a hollow hour-handshaft 13, an also hollow minute-hand shaft 14, which is fastened in theformer with the ability to rotate, and a central second-hand shaft 15respectively with a hand seat 16 for clamping on the clock hands (nowshown), and the hand seat is located before a housing front part 12 usedas a clock face carrier. The hour-wheel and minute-wheel hollow shafts13, 14 are, however, not centered by means of the second-hand shaft 15but instead by means of a support tube 17 on a housing-mounted baseplate 18 surrounding said shafts.

A minute wheel 19 that is rigidly connected to the minute-hand shaft 14is supported axially relative to its hand seat 16 against the base plate18 and carries on its part coaxially an hour wheel 20 that is rigidlyconnected to the hour-hand shaft 13. Both are connected to each other byway of a gearing via an intermediate wheel 21 with the intermediatewheel being driven by the pinion 22 of the minute wheel 19 and thepinion on its part driving the wheel 20 with a pinion 23 while reversingthe direction of rotation and effecting gear ratio reduction. For thispurpose, the intermediate wheel 21 is supported on a fulcrum pin 24between the base plate 18 and a printed circuit board 25 arrangedmounted to the housing. The electromagnetic stepping motor for drivingthe second wheel 26 and the further intermediate wheels (between thestepping motor and the second wheel 26 and between the motor and theminute wheel 19) as well as the complete, transversally operating lightbarrier 55 are not covered in the described step.

The printed circuit board 25 carries on its surface 27, which isdirected away from the base plate 18 and is therefore directed towardsthe housing front part 12, a contact ring 28 that concentricallysurrounds the hour-hand shaft 13 and that is specially mounted orrealized by way of the corresponding course of a conductor path lining.The free front end of a contact finger 29, that is configured as abending spring, is supported, spring-preloaded, against this contactring. The contact finger 29 can be rigidly rotated with the hour-handshaft 13 around the central axis 30 of the clockwork mechanism 11. Thecontact finger is bent out of a contact disk 31 that is punched out ofspringy metal, and said contact disk is pushed with its central opening32 from the hand seat 16 with sliding friction onto the hour-hand shaft13 until it is elastically supported, spring-preloaded, with its contactfinger 29 against the contact ring 28 on the printed circuit board 25;this results in a slight denting of the disk 31 in the area of itscentral opening 32 causing a keying on the external jacket surface ofthe hour-hand shaft 13. A radial recess of the central opening 32 on theexternal jacket surface of the hour-hand shaft 13 is penetrated by anaxis-parallel fin 33 as safety against displacement of the contact disk31 relative to the hour-hand shaft 13.

Hour-contact arches 34, which are insulated relative to one another,extend along a circle that is concentric relative to the contact ring 28on the surface 27 of the printed circuit board 25 in accordance with thehour division on the minute distribution of the clock face, which meanstwelve of them regularly arranged. Above them, an hour-contact-scanningfinger 35 is turning synchronously with the movement of the hour hand,i.e. synchronously with the hour-hand shaft 13; the hour-contact fingeris also bent out of the contact disk 31, as can be seen from thedrawing. This way, it is always that hour-contact arch 34 that isshort-circuited with the contact ring 28 via the two contact fingers29-35 and their joint contact disk 31 that is currently assigned to thecurrent rotation angle position of the hour wheel 20 and therefore to acurrent hour-angle position in front of the clock face. Which of thecontact arches 34 is affected at a given instance is determined via anevaluation circuit 36 that is connected on the printed circuit board 25to the contact arches 34, whereby the current hand position is detected.Suitably, the respectively contacted hour-contact arch 34 is placed onthe ground potential via the contact disk 31 and the contact ring 28, inparticular by way of switching the contact ring 28 to ground potentialvia the conductor path lining of the printed circuit board surface 27.

For a more exact detection of the current angle position of the hourhand, each of the hour-contact arches 34 has assigned anhalf-hour-contact arch 37 on a further circle that is concentricrelative to the axis of the mechanism 30, as can be seen in the secondhalf of each of the hour-contact arches 34. During a rotation of thehour wheel 20, the half-hour-contact arches 37 are contacted one afterthe other by way of a further contact scanning finger 38 protruding fromthe contact disk 31, and that are in the displayed embodiment alsosequentially placed on ground potential via the contact disk 31 and thecontact ring 28. This way, the evaluation circuit 36, which is alsoconnected to the half-hour-contact arches 37, detects via the currentlyprevailing ground potential not only the hour area to which the hourhand is pointing at the current time but also whether it is the firsthalf or—because the associated half-hour-contact arch 37 has in themeantime also been placed on the ground potential—the second half ofthis current hour. This way, the evaluation circuit 36 is able to detectat any time in which hour interval the hour hand is located at a giventime and in what half-hour interval the minute hand, which is coupledwith the former by way of gearing, is located at a given time. Thismeans that, for example, when operation of this radio clockworkmechanism 11 is started up, the current hand position is immediatelyknown with a precision of within half an hour and, at any rate, withoutany long running of the gearing. Without long extended additional handmovement, the exact position of the hands becomes known with the changeto the next half-hour interval because at that time either only the nexthour- or additionally the next half-hour-contact arch 34 and/or 37 aswell is placed on ground potential. An electrically non-conducting gapbetween two sequential hour-contact arches 34-34 ensures that the twoare never simultaneously on ground potential, which is why the hourencoding cannot become ambiguous because the length of the arch gap islarger than that of the contact-making surface of the hour contactfinger 35.

To detect the half-hour change with preciseness, even though ohmiccontact insecurities and play in the gearing lead principally to anon-reproducible exactness of the responsiveness when lowering thecontact potential to ground, the decoding query occurs always exactly atthe time when the movement of the hand releases the path of the light ofthe light barrier 55 upon entering a new half-hour interval. In FIG. 2,this is symbolized with a small circle 101 in the respective angularposition of the hour hand. But in order for there not to be anyinfluences due to the previously mentioned switching insecurities atthat time—because of the play of the gearing and subsequent to e.g.contact bouncing phenomena when approaching the edge of the contactarches 34 and/or 37—but to ensure that quasi-stationary potentialconditions exist, the respective contact arches 34 and 37 become activeeven before the half-hour change on the clock face, as is indicated inthe drawing with extension of the contact arches 34, 37 against themovement direction of the hand of the clock. The lowering of potentialto ground potential has therefore occurred reliably and in a stationarymanner, when the evaluation circuit 36 queries the contact arches inquestion regarding the logical half-hour decoding.

Therefore, in order to detect this half-hour change independently of theresponse precision of the contact finger 38 and/or 29 during the contactchange, a bifurcated or, as shown in FIG. 1, reflective light barrier 55is envisioned. The symbolically demonstrated positioning of at least itsreceiver 39 on the printed circuit board 25 axially below the contactdisk 31, that is constantly at ground potential, has the advantage thatit is electrically well shielded. Used to effect the response of thelight barrier receiver 39 exactly at the half-hour change is—asdescribed in further detail in DE 35 10 861 C2 that was referred toearlier—the course of the light barrier through a hole 57 in theintermediate wheel 21 and through the hour wheel 20, opticallytransparent or equipped with 24 holes 56, that is driven by pinion 22 ofthe intermediate wheel.

In fact, the contact fingers 29, 35, 38 are not, as seen in thesimplified drawing, all arranged along the same radius of the contactdisk 31, but they are offset relative to each other at an angle in orderfor the contact disk 31 to be able to press against the printed circuitboard 25 without keying.

Since the contact disk 31 turns synchronously with the hour wheel 20,which means it turns with the hour hand before the clock face, it isuseful to realize a further contact finger 40 on the contact disk thatserves to trigger an alarm. But to ensure that during its time-keepingrotation said trigger is not continually supported, while makingcontact, on an alarm contact ring 41 on the printed circuit boardsurface 27, an electrically insulating spacer ring 42 is arrangedbetween the two, which can also be electrically conducting if it isinsulated relative to the alarm contact ring 41 by way of a coating orby way of a distance. The distance ring 42 has only at one location ofits circumference axially above the alarm contact ring 41 a radial clickopening 43 for the passage of the alarm contact finger 40. Therefore,when said alarm contact finger reaches this angular position in thecourse of its time-keeping movement with the hour wheel 20, it snapsthrough click opening 43 along a steep click edge 44 until theaxis-parallel contact against the alarm contact ring 41 is achieved.This way, it is placed on ground potential via the contact disk 31 andthe contact ring 28 and which is why an alarm signal is released via theevaluation circuit 36 for broadcast. Employing a lifting ramp 45 withonly a flat incline in comparison to the click edge 44, the alarmcontact finger 40 is lifted up onto the distance ring 42 again, whilethe hour wheel 20 continues to turn, which means the alarm contactfinger is lifted away from the alarm contact ring 41 until the clickoccurs once again after the hour hand completes a rotation.

The distance ring 42 with its click opening 43 is thus, on the whole,mounted to the housing, and thus rigidly attached to its alarm contactfinger 40 relative to the rotation movement of the hour wheel 20. Theangle position of the distance ring 42 with its click opening 43,however, is manually adjustable by its gearing via a front gearing 46,and by way of which the trigger time for the alarm signal can bevariably preset. For this purpose, the distance ring 42 is configured asa radially protruding circling flange on the internal jacket surface ofa internal gear wheel 47 as can be seen in the cross-sectionalrepresentation in the drawing. The internal gear wheel 47 is arrangedradially, with a hollow fulcrum pin 48 projecting from its wheel disk 49at the free front end of which a hand seat 16 is realized for the alarmhand, on the hour-hand shaft 13 in the housing front part 12 andarranged axially between the housing front part 12 and the printedcircuit board 25. For the purpose of arresting the angle position of theclick opening 43 in the distance ring 42 that is preset via the frontgearing 46—against the rotation of the alarm contact finger 40 supportedthereon—a spring arm 50 extends off the wheel disk 49 which is orientedin a parallel direction relative to the housing front part 12 and whichelastically supports itself with its free front end against the internalwall of the housing front part 12 and uses the latter as friction. Asshown in the drawing, it is possible to envision at this location even alatch click that acts as back-stopping device 51 in order to preventthat the click opening 43 is being turned relative to the alarm contactfinger 40 vis-à-vis the steep click edge 44, and that instead it canonly be turned by way of the lifting ramp 45. This ensuressimultaneously that any turning of the distance ring 42 does not resultvia the alarm contact finger 40 in the concomitant rotation of the hourwheel 20, indicating an erroneous display of the hour hand before theclock face.

At any rate, the solution according to the invention provides for anelectromechanical radio clockwork mechanism 11 with analog display forachieving one of many hand-reference positions quickly andautomatically, in particular without the need for a long running of thegearing for moving the clock hands into one of only a few or even into asingle reference position. The detection of attaining the referenceposition, on the other hand, does not require the complexity of theinstrumentation for a multiple digit, binary coded angle sensor with itssusceptibility to multiple contact making, as well as there is no needfor the query of varying spoke widths in the hour wheel representingpoor suitability for miniaturization. Instead, twelve contact arches 34that are assigned to the division of hours on the clock face are scannedat a given time in succession with the rotation movement of the hourwheel 20 thereby providing rough information regarding the current hourorientation of the hour hand in the context of which the current halfhour is queried via another contact arch 37. The moment the query takesplace at the beginning of each half hour is very exactly preset by wayof a sensor in the hand-clockwork gearing, in particular a lightbarrier. For the successive query of the contact arches 34 and 37, thecontact arches 34 and 37 are suitably, via contact fingers 35 and/or 38,placed on ground potential, one after the other, on a joint contact disk31 that rotates with the hour wheel 20 and via a contact ring 28. Thecontact disk 31 can additionally be equipped with an alarm contactfinger 40 that rotates on a spacer ring 42 above an alarm contact ring41 but that contacts at an angular position, which can be preset via aradially oriented, slot-shaped click opening 43 in the spacer ring 42,the alarm contact ring 41 in order to trigger an alarm signal ring 42without the need of having to axially displace any of the wheels thatcarry the hands from the hand clockwork mechanism.

1-13. (canceled)
 14. Radio clockwork mechanism comprising a movable hourhand and a mechanism for determining which hour the hour hand iscurrently indicating, comprising: hour-contact arches assigned torespective hours and spaced apart along a circular path, a scanningmechanism including an hour-scanning device movable synchronously withthe hour hand for sequentially scanning the hour-contact arches andgiving a currently scanned hour-contact arch an electrical potentialdifferent from an electrical potential of all other hour-contact arches,and a querying-mechanism for querying the hour-contact arches fordetermining which has the different electrical potential.
 15. Radioclockwork mechanism claimed in claim 1 further includinghalf-hour-contact arches spaced apart along a circular path concentricwith, and having a different radius than, the circular path of thehour-contact arches; each half-hour-contact arch being associated with arespective hour-contact arch; the scanning mechanism including ahalf-hour-scanning device movable synchronously with the hour hand forsequentially scanning the half-hour contact arches and giving acurrently scanned half-hour contact arch an electrical potentialdifferent from an electrical potential of all other half-hour-contactarches; the querying mechanism arranged for querying the half-hourcontact arches for determining which has the different electricalpotential.
 16. Radio clockwork mechanism as claimed in claim 15 furtherincluding an hour wheel connected to the hour hand; the scanningmechanism further including a contact ring arranged concentricallyrelative to the circular path of the hour-contact arches and having aselected electrical potential; the scanning mechanism including acontact disk rigidly connected to the hour wheel; the hour-scanningdevice including an hour-scanning finger extending from the contact diskand arranged to make contact with the hour-contact arches, the half-hourscanning device comprising a half-hour scanning finger extending fromthe contact disk and arranged to make contact with the half-hour contactarches; and a contact finger extending from the contacting disk and thecontact ring for connecting the hour-scanning finger and the half-hourscanning finger with the potential of the contact ring.
 17. Radioclockwork mechanism as claimed in claim 16 wherein the potential of thecontact ring is ground potential.
 18. Radio clockwork mechanismaccording to claim 16, further including an hour-hand wheel connected tothe hour hand, the querying mechanism including a light barrierextending across a path of travel of the hour hand wheel, wherein thequerying of the hour-contact arches is initiated in response to thebeginning of a half-hour-period.
 19. Radio clockwork mechanism accordingto claim 18 wherein the light barrier is disposed below the contactdisk.
 20. Radio clockwork mechanism as claimed in claim 16 including anhour-hand shaft connected to the hour hand; wherein the contact diskincludes a central opening and is mounted on an external surface of thehour-hand shaft for rotation therewith.
 21. Radio clockwork according toclaim 16 further including an alarm mechanism comprising a spacer ringrotatable relative to the hour hand shaft and including: an alarmopening, an alarm contact ring coaxial with the circular path of thehour-contact arches, and an alarm contact finger extending from thecontact disk and held out of contact from the alarm contact ring by thespacer ring until reaching the alarm opening.
 22. Radio clockworkmechanism according to claim 21 wherein the alarm opening includes firstand second edges, one of which being less steep to raise the alarmfinger out of the alarm opening during rotation of the spacer ring. 23.Radio clockwork mechanism according to claim 21 wherein the spacer ringcomprises part of a gear wheel that is connectable to an alarm hand androtatable about the hour-hand shaft.
 24. Radio clockwork according toclaim 23 wherein the gear wheel carries a spring arm bearing yieldablyagainst an outer housing of the radio clockwork mechanism.
 25. Radioclockwork according to alarm 24 wherein the housing carries a one-waystructure engaging the spring arm for permitting rotation of the spacerring in only one direction.
 26. Radio clockwork mechanism as claimed inclaim 14, further including an hour-hand wheel connected to the hourhand, the querying mechanism including a light barrier extending acrossa path of travel of the hour hand wheel, wherein the querying of thehour-contact arches is initiated in response to the beginning of ahalf-hour-period.
 27. Radio clockwork mechanism according to claim 26,further including a minute hand and a minute hand wheel connectedthereto, and an intermediate wheel for transmitting rotation between theminute hand wheel and the hour hand wheel; wherein the hour hand wheel,the minute hand wheel and the intermediate wheel include respectivelight emitting passages that are alignable to conduct the light barrierat the beginning of the half-hour.